The present invention relates to an electronic drum.
In a conventional electronic drum, a drum head is struck with sticks and vibrations are converted to electrical signals. The generation of musical tones (electronic tones) in an electronic sound source device (e.g., a PCM or FM sound source) is controlled to produce electronic tones at a loudspeaker according to waveshape information (e.g., time position and volume level) for the electrical signals. In order to achieve the above operation, the following conditions are required: (1) the output (sensitivity) of a pickup unit is uniform regardless of the struck position of the drum head; (2) a signal magnitude changes depending on the striking forces in order to satisfy the player's feel; and (3) sticking is similar to an acoustic drum. It is therefore obvious that the performance of the electronic drum is determined by the drum head material and drum head assembly. Various types of conventional drum heads have been proposed, as described in Japanese Utility Model Publication No. 59-39753 and Japanese Utility Model Prepublication Nos. 55-97792 and 58-113070.
In an electronic percussion musical instrument described in Japanese Utility Model Publication No. 59-39753, the edges of two vibration films are adhered through a cushion member and a pickup to constitute a drum head. The means for supporting under tension the drum head has a complicated structure and is difficult to handle. In addition, sensitivity varies depending on the striking position, a decisive drawback. In an electronic percussion musical instrument in Japanese Utility Model Prepublication No. 55-97792, a tray is arranged at an opening of a musical instrument body and a cushion member is accommodated therein. The cushion member is covered with a striking film. The striking film must be supported with a predetermined tension force. The structure is complicated and subject to sensitivity variations in the same manner as the instrument in Japanese Utility Model Publication No. 59-39753. In a drum trainer described in Japanese Utility Model Prepublication No. 58-113070, a rubber foamed member having a rubber hardness of 8.degree. to 10.degree. is formed on the surface of a base, and a pseudo head is adhered to the rubber foamed member. Although good sticking feel can be achieved, this apparatus is only a trainer and is thus unsatisfactory as a pad for an electronic drum.
Another conventional electronic drum is illustrated in FIG. 5. A tensed drum head 1 is supported on a body 2. A cushion 4 is inserted between the drum head 1 and an intermediate plate 3. A dynamic speaker as a microphone 5 is mounted on the lower surface of the intermediate plate 3. In this electronic drum, although sticking feel is similar to an acoustic drum, high-frequency characteristics are poor, and sophisticated stick work tends to be lost. In addition, the microphone 5 itself has a larger thickness, and thus the drum itself becomes thicker.